B) Several factors contribute to the maintenance of grassland ecosystems. (i)
Describe one way that grazing animals, such as bison or cattle, help to maintain grassland ecosystems.
(ii)
Explain how seasonal fires benefit grassland ecosystems.

The difference of sample means of two populations is 55.4, and the standard deviation of the difference of sample means is 28.1. which statement is true if we are testing the null hypothesis at the 95% confidence level? a. the difference of the two means is significant, so the null hypothesis must be rejected. b. the difference of the two means is significant, so the null hypothesis must be accepted. c. the difference of the two means is not significant, so the null hypothesis must be rejected. d. the difference of the two means is not significant, so the null hypothesis must be accepted.